A 72 year old female presented to the ED after an episode of syncope. She denied chest pain or palpitations prior to or after the event. The History was positive for generalized malaise with recent flu like symptoms. Significant examination findings were of a healing lesion behind her left knee from a camping trip in Connecticut four weeks ago. EKG showed sinus rhythm with a first-degree AV block, PR interval of 236 and a new left bundle branch block (LBBB) compared to her EKG one month prior (shown below). Cardiac enzymes were negative. Laboratory data showed mild leukopenia and thrombocytopenia. Cardiology was consulted. Echocardiogram showed no wall motion abnormality with preserved ejection fraction. Peripheral blood smear was ordered considering the hematological abnormality and showed parasites in the red cells, confirmed to be Babesiois. Babesios was a valid explanation of this patient’s symptoms of myalgia, hematological lab findings and possible vaso-vagal syncope but not the LBBB. Oral Atovaquone and azithromycin was initiated. The possibility of a co-infection with Lyme disease was entertained and Lyme titers sent. On day 2 of admission Lyme IgG and IgM serology was positive and intravenous (IV) Ceftriaxone started for Lyme carditis. Western blot confirmed Lyme disease. No further cardiac workup was pursued
Discussion:
Lyme carditis occurs in approximately 1% of reported cases. The most common Cardiac manifestations are atrioventricular nodal blocks. A LBBB though not the most typical conduction abnormality has been documented as a possible sequelae. It is important to recognize and treat Lyme carditis to prevent unnecessary cardiac interventions such as temporary/permanent pacemakers, and cardiac catheterization as the heart blocks are usually temporary resolving in 1-6 weeks with antibiotic therapy. Whether Lyme carditis should be treated with IV antibiotics was discussed in the care of this patient. IV therapy is recommended for patients with a high degree block (second degree type 2/ third degree AV block), as well as those with first degree heart block with a PR interval ≥300ms. Our patient was discharged on oral doxycycline
Conclusions:
A new LBBB is always worrisome for myocardial infarction. Our case highlights that we should not anchor our diagnosis of a new LBBB as an acute coronary syndrome equivalent only and stands as reminder that Lyme carditis should remain a differential in high risk areas with history or physical findings suggestive of tick exposure